1. Field of the Invention
The present invention relates to a system and a method for making use of rainwater falling on and collected at houses and buildings.
2. Description of the Related Art
In general, the volume content or the filling ratio of water molecules in water is at most about 34%. To this end, water is compared to sponge having a number of air gaps in it. Since water molecules are chemical compounds consisting of oxygen and hydrogen, they attract both cations (positive ions) and anions (negative ions)) and trap various substances in the gaps among the water molecules.
Water is categorized as a solvent with a property of dissolving materials very well. On the other hand, most materials existing on the earth are categorized as solutes that are soluble in water. As commonly understood, “water”, including the tap water, is a mixture of solvent (i.e., a gathering of water molecules) and solutes, such as minerals.
“Pure water” is artificial water, which is produced by physically filtering water, i.e., a mixture of water molecules and various solutes, and removing such solutes and impurities. Pure water has a high absorbency, which is an essential element of its function as a solvent. Pure water is called “hungry water” because of its absorbency, and is used to rinse IC substrates because of its cleansing ability. Pure water is also used as a raw material for drinking water and various beverages because it contains few impurities or solutes. Thus, pure water has been broadly applied to various uses in these years.
While pure water is an artificially filtrated product, rain and snow are products of the nature and closest to pure water because they are gatherings of pure water molecules evaporating in the atmosphere.
The quantity of solutes contained in a unit volume of water is expressed as hardness. The hardness of tap water in Japan is about 70 mg to 170 mg per liter, and is categorized as soft water containing few solutes by global standards. The hardness of tap water in mountainous areas of Europe is about 370 mg to 400 mg per liter, and is categorized as hard water. The hardness of rainwater is much lower even than soft water, at less than 20 mg per liter. This means that rainwater is supersoft water containing little solute and extremely close to the gathering just of water molecules that is, pure water.
The less solutes contained in water, the easier it is to filtrate or purify, and the more possible to treat without using harmful chlorine or other chemicals. Accordingly, rainwater can be recycled into safe natural water. Such recycled rainwater is superior in absorbency, and has a broad range of uses, including rinsing water or drinking water. As long as a reliable filtering means is used and the quality of rainwater is guaranteed, rainwater can be optimally used in various ways, including watering garden plants, washing cars, sanitary water, kitchen water and drinking water.
However, with the conventional techniques, rainwater has not been positively or practically utilized, in spite of its superior nature and possibility as the optimum living water. So far, rainwater has only been treated as wastewater, and recycling of rainwater has not been considered sufficiently.